Preheat oven to 425.
Put butter in a medium sized bowl.
Add in olive oil, rosemary, garlic and lemon zest.
Stir to combine. Set aside.
Generously season chicken with salt and pepper, including inside of the cavity.
Brush the butter mixture onto the chicken generously covering up all of the chicken.
Squeeze the juice of 1 lemon all over the chicken.
Place chicken in roasting pan.
Cook for 45 minutes and then baste.
Return to oven and cook for another 15 minutes or until golden. Lightly tent with foil if chicken is browning too quickly.
Let chicken cool for 15 minute before serving.